function Judge()
    A=[1,0.4,0.4;0.4,1,0.8;0.4,0.8,1];
    b=[1;2;3];
    p=judgeJacobi(A,b)
    p=judgeGS(A,b)
    A2=[1,2,-2;1,1,1;2,2,1];
    b2=[1,1,1];
    p=judgeJacobi(A2,b2)
    p=judgeGS(A2,b2)
    function [p]=judgeJacobi(A,b)
        D=diag(diag(A));
        L=-tril(A,-1);
        U=-triu(A,1);
        B=D\(L+U);
        eig(B)
        p=max(abs(eig(B)));
    end
    function [p]=judgeGS(A,b)
        D=diag(diag(A));
        L=-tril(A,-1);
        U=-triu(A,1);
        B=(D-L)\U;
        eig(B)
        p=max(abs(eig(B)));
    end
end